A previously proposed injector, which injects fuel with a very high injection pressure of over 100 MPa, receives the fuel through an inlet connector (see, for example, Japanese Unexamined Patent Publication No. 2006-316741A).
Specifically, with reference to FIGS. 3 and 4, a previously proposed injector 100 includes a main body 102, an injection nozzle 103 and an inlet connector 101. The main body 102 receives fuel from a fuel supply source. The injection nozzle 103 is securely connected to an axial distal end portion of the main body 102 and injects the fuel upon receiving the fuel from the main body 102. The inlet connector 101 is securely connected to a lateral side of the main body 102 and forms a fuel receiving portion to supply the fuel to the main body 102. The inlet connector 101 is securely screwed into a cylinder head (not shown) of the internal combustion engine and is engaged with the main body 102 with an axial force generated by the screwing of the inlet connector 101 into the cylinder head, so that the inlet connector 101 is securely connected to the main body 102.
Here, the main body 102 includes a connector hole 105 and an axial flow passage 106. The connector hole 105 receives a distal end portion of the inlet connector 101. The axial flow passage 106 extends in parallel with an axial direction of the main body 102 and guides the fuel, which is received from the inlet connector 101, to the injection nozzle 103. The distal end portion of the inlet connector 101 forms a contact circle 108 to seal the fuel through circular contact of the distal end portion of the inlet connector 101 against a tapered hole surface 107, which forms the connector hole 105.
In the main body 102 of the injector 100, a communication hole 110, which is coaxial with the connector hole 105, is formed, and the connector hole 105 and the axial flow passage 106 are communicated with each other in a radial direction through the communication hole 110 rather than directly communicating the connector hole 105 and the axial flow passage 106 with each other by connecting the axial flow passage 106 to the connector hole 105.
Specifically, in the case where the connector hole 105 and the axial flow passage 106 are directly communicated with each other, a surface area of an intersection between the connector hole 105 and the axial flow passage 106 may become small to possibly cause formation of a flow restriction, and an acute projecting portion having a small wall thickness may be formed to possibly cause a reduction in a compression strength. Therefore, in the main body 102 of the injector 100, the connector hole 105 and the axial flow passage 106 are communicated with each other in the radial direction by the communication hole 110, which is coaxial with the connector hole 105.
However, due to the development in the increasing of the injection pressure in late years, it has been demanded to increase the compressive strength in a connecting and intersecting structure of the connector hole 105, the axial flow passage 106 and the communication hole 110 in the main body 102. Specifically, a stress, which is caused by an axial force generated by the screwing of the inlet connector 101, and a stress, which is caused by a pressure of the received fuel, tend to be concentrated at an intersection between the connector hole 105 and the communication hole 110, an intersection between the communication hole 110 and the axial flow passage 106, and adjacent areas around these intersections. Thereby, it has been demanded to improve the compressive strength.
Here, in view of a location of a space 112, which accommodates other devices, such as a solenoid valve 115, and a location of other fuel flow passages, the axial flow passage 106 is provided at a location, which is spaced from the axis of the main body 102 and is adjacent to a radially outer side of the main body 102. Therefore, the intersection between the connector hole 105 and the communication hole 110 and the intersection between the communication hole 110 and the axial flow passage 106 are concentrated in a narrow range, which is adjacent to the radially outer side of the main body 102.
Furthermore, an axis O6 of the connector hole 105 and of the communication hole 110 is perpendicular to an axis O5 of the axial flow passage 106. The connector hole 105 is formed as a tapered hole having a large diameter. Therefore, the fuel flow passage, which extends through the connector hole 105, the communication hole 110 and the axial flow passage 106 and is bent by 90 degrees, forms an acute projecting portion 113 at an inner side area of this bent located on an inner side of the bent.
As a result, even in the projecting portion 113, the stress is concentrated at a flow passage adjacent layer 114, which is located at a radially inner side part of the projecting portion 113 along the axial flow passage 106 and is narrow. Thus, in order to increase the injection pressure, it is required to alleviate the concentration of the stress at the flow passage adjacent layer 114.